Air dehumidifier for pneumatic brake force producing device

ABSTRACT

The invention relates to a pneumatic brake force producing device comprising at least one suction device for the surrounding air. The aim of the invention is to prevent the condensation of air humidity in the brake force producing device. According to the invention, this can be achieved in an especially reliable manner by passing the aspirated air through a condenser before it enters the brake force producing device. The air-guiding parts in said condenser are at a lower temperature than the air-guiding parts of the brake force producing device in such a way that enough air humidity from the air condenses in the condenser to avoid further condensation in the brake force producing device.

[0001] The invention relates to a pneumatic brake force producing device having at least one intake device for the surrounding air.

[0002] During the operation of the service brake, an air exchange takes place in the case of a pneumatic brake force producing device between the pressureless spaces of the pneumatic brake force producing device and the environment.

[0003] Systems are known which take in air directly from the environment, in which case special take-in elements hinder the taking-in of dust and/or splashing water.

[0004] When the surrounding conditions change, for example, the temperature of the surrounding air, the components of the brake force producing device adapt to the new surrounding conditions only in a delayed manner.

[0005] If the taken-in air is, for example, warmer than the pneumatic brake force producing device, which happens, for example, when leaving a tunnel, there is the risk of a condensation of the air humidity in the pneumatic brake force producing device. This may lead to a corrosion within the pneumatic brake force producing device. This corrosion may result in operating disturbances or failure of the brake forcing producing device.

[0006] The present invention is therefore based on the problem of providing a device which reduces the danger of a condensation of the air humidity in the brake force producing device. The device is to be cost-effective and should require no maintenance.

[0007] This problem will be solved by means of the characteristics of the main claim. For this purpose, the intake device has a condenser consisting of at least one pipe guiding the intake medium to the brake force producing device. In addition, at least parts of the pipe are arranged in a zone which, in the regular operation, is cooler than the air-guiding parts of the brake force producing device.

[0008] The taken-in air is sucked through the condenser into the pneumatic brake force producing device. In the parts of the pipe of the condenser which are situated in the cooler zone, the air guided in the pipes will be cooled. Since, at the same absolute humidity of the air, the relative air humidity of cold air is higher than that of warm air, in the area of the pipe, the condensation of the air will occur in the cooler zone inside the pipe. During the flow through the pipe, the temperature of the air approaches the temperature of the interior wall of the pipe. Since the air-guiding parts of the brake force producing device, in the regular operation, are warmer than the pipe, the temperature of the air remains the same when entering the brake force producing device or it heats up. In this case, the relative air humidity remains the same when leaving the intake device or its falls as the temperature increases. Since the relative humidity is below the saturation point of the air leading to a condensation at this temperature, the risk of a condensation of the air within the pneumatic brake force producing device is considerably reduced. As a result of this simple construction, this device is cost-effective. Since it contains no movable parts or parts subject to wear, it is maintenance-free.

[0009] In this case, the pipe may be a pipe or a pipe system. The cross-section is, for example, round, elliptical, rectangular. polygonal, etc. The pipe may, for example, also comprise a duct or a hose or may be a combination of various elements.

[0010] The entire pipe may be arranged in the cool zone or may, for example, be cooled separately.

[0011] The condenser is, for example, a pipe whose free end represents a condenser intake opening. The free end may end in the proximity of a heat-storing body, for example, in the proximity of the bottom of a container which is open toward the top. Inside the container, the temperature profile adapts itself from the top to the bottom to the surrounding temperature. The cool air layers situated at the bottom act in a heat-absorbing fashion. The area of the highest condensation will then be the area of the free end of the pipe.

[0012] The slope of the pipe is, for example, greater than the maximal slope and/or the inclination of the line (typing mistake? road? translator) carrying the vehicle. As a result, the condensate, which forms during the flow through the pipe, can flow off through the pipe independently of the vehicle inclination. The risk of a condensate intake is thereby reduced.

[0013] The heat exchange surface of the condenser toward the exterior medium is, for example, larger than that toward the taken-in air. Thus, on its exterior side, the pipe can be maintained at the temperature of the heat-storing medium surrounding it, while the temperature of the air guided on the inside approaches this temperature. Instead of air, the cooling medium may also be another gas or a liquid.

[0014] The pipe consists, for example, of a corrosion-resistant material.

[0015] Additional details of the invention are contained in the subclaims and in the following description of a schematically illustrated embodiment.

[0016]FIG. 1 is a view of the device for reducing the humidity of the intake air at a brake force producing device.

[0017]FIG. 1 shows a pneumatic brake force generating device (10) having an intake device (20) for the air exchange when operating the brake between the pressureless spaces of the brake force generating device (10) and the surroundings (5). The intake device (20) comprises a coiled piping (22) by way of which, for example, air is taken from the surroundings (5) into the brake force producing device (10). The coiled piping (22) is disposed in a container (30) open toward the top.

[0018] The coiled piping (22) is, for example, a perpendicularly arranged, helically extending pipe of a constant cross-section. On the bottom, it has a free end (23) which comprises an intake opening. Approximately eight pipe turns are disposed above one another. The diameter of the coiled piping (22), in the lower six pipe turns, amounts to approximately 16 times the pipe diameter. These pipe turns have a constant slope of approximately 1.25 times the diameter of each pipe turn.

[0019] The diameter of the uppermost one-and-a-half pipe turns amounts to approximately 60% of the diameter of the coiled piping. At the top, the coiled piping (22) changes into a straight pipe piece (28) which is connected by means of a screwed pipe connection (26) with the intake connection piece (12) of the brake force producing device (10).

[0020] In the proximity of the screwed pipe connection (26), the intake connection piece (12) is fastened in a passage bore (36) of the container (30) by means of a screwed connection (13).

[0021] The container (30) has an approximately cylindrical jacket (32) which tapers in the upward direction to approximately three fourths of its lower wall thickness. The jacket (32) is by approximately 20% higher than the coiled piping (22). The bottom (33) of the container (30) has approximately the thickness of the upper edge of the jacket (32) and drops off toward one side. The gradient corresponds over the width illustrated in FIG. 1 approximately to twice the thickness of the bottom (33). In FIG. 1, the portion of the bottom (33) which is situated lower is arranged on the side of the container (30) facing away from the brake force producing device (10).

[0022] In this area of the bottom (33), a, for example, vertical passage bore (34) is arranged which is countersunk on the interior side of the container (30). The diameter of this bore (34) corresponds approximately to the diameter of the pipe of the coiled piping (22).

[0023] During the drive of the vehicle, the air for the brake force producing device (10) is taken in from the surroundings through the coiled piping (22).

[0024] During a long drive with normal average braking operations at a uniform surrounding temperature, the coiled piping (22) has assumed an insignificantly lower temperature than the air-guiding parts of the brake force producing device (10). As a result of the sporadic activation of the brake force producing device (10), the temperature of the air-guiding parts of the brake force producing device (10) is, as a rule, necessarily above the temperature of the air surrounding the vehicle. The interior and the exterior area of the brake force producing device (10) have approximately the same temperature. During the intake of the medium, the relative air humidity remains approximately constant because of the uniform temperature of the medium. The humidity of the air therefore does not condense on the walls of the coiled piping (22) or on the interior walls of the air-guiding parts of the brake force producing device (10).

[0025] During a drive from a warmer region into a cooler one, for example, when driving into a tunnel, the temperature of the taken-in surrounding air (5) will drop faster than the temperature of the brake force producing device (10) and of the coiled piping (22). The now taken-in colder air can absorb only a lower amount of humidity than the air in the warm brake force producing device (10). When entering the condenser (22) and the brake force producing device (10), the air is warmed. In this case, its relative humidity will fall. No condensate will form in this uncritical case.

[0026] When, in contrast, the vehicle drives from a cooler region into a warmer one, as, for example, when exiting a tunnel, when driving downhill in a mountainous area or when driving into buildings or hangars, the surrounding air (5) warms up more rapidly than the interior of the brake force generating device (10) or the coiled piping (22). The amount of humidity in the warm surrounding air (5) will now be higher than that in the colder air in the brake force producing device (10). When flowing through the cool coiled piping (22), the taken-in air is cooled. In this case, the relative air humidity exceeds the saturation point. A portion of the air humidity condenses on the interior walls of the coiled piping (22). The amount of humidity in the air decreases. As a result of the ascending arrangement of the coils (22), the forming condensate flows off into the container (30) and there flows through the opening (34) to the outside. Because of its position protected from the air stream, in the embodiment, the coolest point of the condenser (22) is the free end (23). Here, the highest condensation will take place. The condensation therefore decreases along the condenser (22) from the free end (23) to the intake connection piece (12) of the brake force producing device (10).

[0027] In order to avoid corrosion, the coiled piping (22) may be constructed of a low-corrosion steel, for example, X 5 CrNi 18 9.

[0028] During the flow through the coils (22, the temperature of the air will asymptotically approach the coil temperature. Because the exterior heat exchange surface of the coils (22) is larger than the interior one, the outer wall surface of the coiled piping (22) retains approximately the temperature of the heat-storing container (30) surrounding it.

[0029] The container (30) is, for example, produced of a material suitable for casting. It forms a heat-storing body which surrounds the coiled piping (22). The coldest zone inside the container (30) is the area of the bottom (33). In this zone, the temperature rise of the air is delayed in comparison to the surroundings.

[0030] List of Reference Numbers

[0031]5 surroundings, surrounding air

[0032]10 brake force producer

[0033]12 intake connection piece

[0034]13 screwed connection

[0035]20 intake device

[0036]22 coiled piping, pipe, condenser

[0037]23 free end

[0038]26 screwed pipe connection

[0039]28 straight pipe piece

[0040]30 container

[0041]32 side wall, jacket

[0042]33 bottom

[0043]34 passage bore in (33)

[0044]36 passage bore in (32) 

1. Pneumatic brake force producing device having at least one intake device for the surrounding air, characterized in that the intake device (20) comprises a condenser for condensing out air humidity which consists of a pipe (22) feeding the intake air to the brake force producing device (10), in that at least portions of the pipe (22) are arranged in a zone which are cooler (at least portions of the pipe (22) arranged in a zone are cooler ?? translator) in the regular driving operation than the air-guiding parts of the brake force producing device (10) connected behind the condenser.
 2. Pneumatic brake force producing device according to claim 1, characterized in that the pipe (22) comprises a free end (23) and in that heat is withdrawn from the pipe (22) at least in the area of the free end (23) by means of a heat-storing body.
 3. Pneumatic brake force producing device according to claim 1, characterized in that the inclination of the pipe (22) from the free end (23) to the brake force producing device (10) is greater than the maximal inclination and/or slope of the line (road? translator) carrying the vehicle.
 4. Pneumatic brake force producing device according to claim 1, characterized in that the heat exchange surface of the condenser with the exterior medium is larger than with the interior medium.
 5. Pneumatic brake force producing device according to claim 1, characterized in that the pipe (22) consists of a corrosion-resistant material.
 6. Pneumatic brake force producing device according to claim 1, characterized in that at least parts of the pipe (22), including the free end (23), are arranged inside a container (30) provided with at least one opening (34) in the bottom area. 